It can be cumbersome to type in the login and password every time you connect using OpenVPN. It has a feature named
auth-user-pass where you can provide the login and password in a file.
Put your login and password in a file, one on each line.
If you are using a OpenVPN config file to connect, indicate the above file in it:
Tried with: OpenVPN 2.3.7 and Ubuntu 15.10